The proportion of days in the United States that are warmer than the long-term average increased from 42 percent in 1964 to 67 percent today, according to an analysis of 3.2 million temperature anomalies over the last 50 years. READ MORE

New York-based company Enigma.io examined data from 2,716 U.S. weather stations to track temperature anomalies over the past 50 years. An interactive version of this graphic, which includes maps, is available on Enigma.io's site. The company found that since 1964, temperature anomalies characterized as warm or “strong warm” have increased by an average of 0.5 percent a year. Enigma’s data show, for example, that in 2012, 84 percent of temperature anomalies in the U.S. skewed on the warm side. (Image credit: Enigma Labs)